A lot of my favorites have been named already, especially John Wiese who's done great things in many contexts, under his own name or with Sissy Spacek. I also enjoyed his tenure with Bastard Noise, for example Descent to Mimas on Groundfault still sounds great to me. It tells a story without being cheesy.
I have to mention Tom Smith of TLASILA, who's had some interesting side projects over the years. His initial collaboration with Kevin Drumm, Reconquer Sleep or Disappear, is a highlight. From my understanding, speaking to Drumm, it's principally Tom re-working material the former provided, and adding a lot of his own special sauce.
I'm not sure if you'd call Miss High Heel a collaboration or more some kind of noise rock supergroup (Tom, Weasel Walter, Azita Youseffi, Jim O'Rourke, Marlon Magas, etc.) but The Family's Hot Daughter is one hell of a journey, not quite on the level of the Shave's Wigmaker, but really out there.
Not nearly as noisy, but really good for the Schimpfluch-inclined, is the Ohne record on Mego: another case where it's more a new group than a specific collaboration, but assembling Tom with Dave Phillips, Reto Mader, and Daniel Lowenbruck was pretty genius. Wish they'd done more.
Back to noise: the Evil Moisture/Macronympha collaboration on RRR, The Tentacles of the Octopus sometimes compete against each other, is some of my favorite ever noise. From my understanding, according to what Andy said on an episode of Noisextra, it's him re-working source material from Macro's Super Oxide tape. With all the killer Macro examples in this thread, a rare case of Joe giving up the reins?
Lastly, more on the experimental side, not harsh at all, are the Nurse With Wound collaborations with Graham Bowers. Probably my preferred later NWW material, because it's really dense and layered, lots of sounds stacked and folded on top of each other. That's generally how I like my noise also. Parade, Rupture, and Excitotoxicity are real winners.
